Pneumatically operated actuator

ABSTRACT

A pneumatically actuated operator for altering the stresses in a piezoelectric crystal means for spark igniting purposes and the like, the actuator having a movable wall that cooperates with a housing to define a chamber therebetween. The actuator has a first passage provided with a valve seat leading to the chamber and is adapted to be interconnected to a pneumatic source. The actuator has a second passage provided with a valve seat leading to the chamber and is adapted to be interconnected to the atmosphere. A single valve member is movably carried by the housing for opening the valve seat of the first passage and closing the valve seat of the second passage when the movable wall is in a predetermined deactuated stroke position thereof. The single valve member is adapted to close the valve seat of the first passage and open the valve seat of the second passage when the movable wall is in a predetermined actuated stroke position thereof whereby the movable wall is cycled between the predetermined positions thereof as long as the pneumatic source is interconnected to a chamber.

United States Patent [15] 3,691,906 1451 Sept. 19, 1972 Kreuter 1541PNEUMATICALLY OPERATED ACTUATOR [72] Inventor: Kenneth G. Kreuter,Goshen, Ind. [73] Assignee: Roberlshaw Controls Company,

Richmond. Va. [22] Filed: May 4, 1970 [211 App]. No.: 46,581

Related US. Application Data [62] Division of Ser. No. 749,745, Aug. 2,1968,

Pat. No. 3,634,706.

[52) US. Cl. ..9l/222, 91/398, 91/469 [51] Int. Cl. ..F01l 21/04, Fl 5b13/042 [58] Field of Search ..91/222, 398, 469

[ References Cited UNITED STATES PATENTS 2,649,076 8/1953 Dupre ..91/3982,649,332 8/1953 Rappl ..9l/398 3,082,748 3/1963Vogel..........................91/222 Primary Examiner-Paul E. MaslouskyAttorney-Amine Jackson. Jr., Robert l... Marben and Candor. Candor 8r.Tassone ABSTRACT A pneumatically actuated operator for altering thestresses in a piezoelectric crystal means for spark igniting purposesand the like, the actuator having a movable wall that cooperates with ahousing to define a chamber therebetween. The actuator has a firstpassage provided with a valve seat leading to the chamber and is adaptedto be interconnected to a pneumatic source. The actuator has a secondpassage provided with a valve seat leading to the chamber and is adaptedto be interconnected to the atmosphere. A single valve member is movablycarried by the housing for opening the valve seat of the first passageand closing the valve seat of the second passage when the movable wallis in a predetermined deactuated stroke position thereof. The singlevalve member is adapted to close the valve seat of the first passage andopen the valve seat of the second passage when the movable wall is in apredetermined actuated stroke position thereof whereby the movable wallis cycled between the predetermined positions thereof as long as thepneumatic source is interconnected to a chamber.

2 Claims, 8 Drawing Figures l3 l8 (5 I? 30 I 31 \ACUUM SOURCE SELECTORVALUE PATENTEDSEP I 9 I972 SHEET 3 BF 4 iiiie fii PAHENTEDSEP 19 I9123.691. 906

SHEET u (If 4 PNEUMATICALLY OPERATED ACTUATOR This application is adivisional U.S. Pat. application of its co-pencling parent application,Ser. No. 749,745, filed Aug. 2, 1968, now U.S. Pat. No. 3,634,706, andis assigned to the same assignee to whom the parent application isassigned.

This invention relates to improved apparatus for altering the stressesin a piezoelectric crystal means to cause sparking for ignition purposesor the like.

It is well known that a piezoelectric crystal means can have theinternal stresses therein altered in a manner to produce an electricalpotential at an electrode interconnected to such crystal means wherebywhen the magnitude of the potential differential between that electrodeand another electrode reaches a predetermined point, sparking is createdacross the spark gap between such electrodes and such sparking can beutilized to ignite the gaseous fuel and the like issuing from a burnermeans disposed closely adjacent the spark gap.

Therefore, it is a feature of this invention to provide improved meansfor altering the stresses of such a crystal means.

In particular, the illustrated embodiment of this invention has thepiezoelectric crystal means disposed between the opposed ends of a pairof pivotally movable arms that have their outer free ends moved towardand away from each other by a pneumatically operated actuatorinterconnected thereto by cam means whereby the crystal means iscompressed as the arms move toward each other and has the compressionthereon relieved as the arms move away from each other, thepneumatically operated actuator of this invention automatically cyclingitself between its deactuated position and its actuated position as longas a pneumatic source is interconnected thereto whereby it can be seenthat the actuator of this invention can be utilized for purposes otherthan operating the ignition means of this invention.

Accordingly, it is an object of this invention to provide an improvedpneumatically operated actuator having one or more of the novel featuresset forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from areading of this description which proceeds with reference to theaccompanying drawings forming a part thereof and wherein:

FIG. I is a top perspective view of the improved piezoelectric crystalactuator of this invention.

FIG. 2 is an enlarged, crosssectional view taken on line 2-2 of FIG. Iand schematically illustrates the ignition system of this invention. thepneumatically operated actuator being disposed in its predetermineddeactuated stroke position.

FIG. 3 is a fragmentary cross-sectional view taken substantially on line3-3 of FIG. 1.

FIG. 4 is a cross-sectional view taken substantially on line 4-4 of FIG.2.

FIG. 5 is a view similar to FIG. 2 and illustrates the pneumaticallyoperated actuator in its predetermined actuated stroke position.

FIG. 6 is a view similar to FIG. 5 and illustrates the pneumaticallyoperated actuator as it starts to move from its predetermined actuatedstroke position back to its predetermined deactuated stroke position.

FIG. 7 is a view similar to FIG. 6 and illustrates the pneumaticallyoperated actuator just before it reaches its predetermined deactuatedstroke position.

FIG. 8 is an exploded perspective view of the various parts of theactuating structure of FIG. 1.

While the various features of this invention are hereinafter describedand illustrated as being particularly adapted to provide sparking forigniting burner means or the like, it is to be understood that thevarious features of this invention can be utilized singly or in anycombination thereof to provide means for altering stresses inpiezoelectric crystal means for any desired purpose.

Therefore, this invention is not to be limited to only the embodimentillustrated in the drawings because the drawings are merely utilized toillustrate one of the wide variety of uses in this invention.

Referring now to FIGS. 1 and 2, the improved ignition means of thisinvention is generally indicated by the reference numeral 10 andcomprises a housing means or frame means 11 carrying a piezoelectriccrystal means or stack, generally indicated by the reference numeral l2,for creating an electrical potential at an electrode I3 that is spacedfrom a grounded pilot burner means 14 and defines a spark gap l5therewith. In this manner, when the stresses in the piezoelectriccrystal means 16 of the crystal stack l2 are altered in the mannerhereinafter described and the potential difference between theelectrodes I3 and 14 reaches a certain magnitude, electrical sparking iscreated across the spark gap 15 to ignite fuel issuing from an outletmeans 17 of the pilot burner means 14, the ignited pilot burner means 14now being adapted to ignite fuel issuing from a main burner means 18disposed adjacent thereto.

The crystal stack 12 includes a pair of pressure pad or anvil means 19and 20 respectively being disposed against the opposed ends 21 and 22 ofthe crystal means 16 and projecting outwardly from the opposed ends of abore means 23 passing through the housing means or frame means I1 andtelescopically receiving the crystal means 16 and pressure pad means 19and 20 therein.

The pressure pads 19 and 20 each has the outer ends 24 and 25 thereofreceived in recesses 26 and 27 formed in a pair of arms 28 and 29pivotally mounted together at their upper ends 30 and 31.

In particular, reference is now made to FIGS. 3 and 8 wherein the arms28 and 29 each has a pair of like cars 32 and 33 extending at rightangles thereto and in spaced relation to receive the upper end 34 of thehousing means or frame means 11 therebetween with the ear 33 of the arm28 overlapping with the car 32 of the arm 29 and with the ear 32 of thearm 28 overlapping with the ear 33 of the arm 29 as illustrated in FIGS.I and 3, the arms 28 and 29 being identical except that the arm 29 isturned relative to the arm 28 as illustrated in FIG. 8.

The ears 32 of each arm 28 and 29 have outwardly extending threadedstuds 35 adapted to be respectively received through openings 36 in theears 33 of the arms 28 and 29 and be secured thereto by suitable nuts 37as illustrated in FIGS. 1 and 3 whereby the arms 28 and 29 areeffectively pivotally mounted to each other at the upper ends 30 and 31thereof.

The lower ends 38 and 39 of the arms 28 and 29 each has a bore 40passing therethrough to be operatively interconnected to the pneumaticactuator of this invention that is generally indicated by the referencenumeral 41 in FIG. 2 and provides part of the housing means or framemeans 1 1 previously described.

The pneumatically operated actuator 41 of this invention as illustratedin FIG. 2 comprises a movable wall means 42 formed from a flexiblediaphragm 43 having its outer periphery 44 secured to the housing means11 in any suitable manner and its inner end or periphery 44' secured toa plate member 45 whereby the movable wall means 42 cooperates with acutout 46 in the lower end 47 of the housing means 11 to define achamber 48 between the housing means 11 and the movable wall means 42.

The plate 45 of the movable wall means 42 has a pair of arms 49 and 49'extending outwardly therefrom in spaced relation and are adapted toreceive a pivot pin 50 in like bores 51 and 51' formed at the lower endsthereof as illustrated in FIGS. 2 and 4.

A plate 52 has its right hand end 53 as illustrated in FIGS. 2 and 4pivotally mounted to the lower end 39 of the arm 29 by a pivot pin 54passing through the bore 40 in the arm 29 and an aligned bore 55 of theplate 52. A circular opening 56 passes through the medial portion of theplate 52 so as to telescopically receive the pin 50 of the actuator arms49 and 49' as illustrated in FlGS. 2 and 4.

The left hand end 57 of the plate 52 has a circular bore 58 passingtherethrough and rotatably receiving a cylindrical cam member 59 thereinas illustrated in FIGS. 2 and 4, the cylindrical cam member 59 beingintegrally interconnected to a cam arm 60 that has its right hand end 61pivotally mounted to the actuator arms 49 and 49' by the pin 50 passingthrough a bore 62 therein as illustrated in FIG. 4.

As illustrated in FIGS. 2 and 8, the cylindrical cam member 59 has abore 63 passing therethrough in offset relation to the longitudinal axisof the cylindrical cam 59 and substantially tangent to the outerperipheral surface thereof. A pivot pin 64 is disposed in the offsetbore 63 of the cam member 59 and is held in position by a nut 65threaded thereon, the pivot pin 64 also passing through the bore 40 atthe lower end 38 of the arm 28 so as to pivotally interconnect the arm28 to the cam member 59.

When the actuator 41 is operated in a manner hereinafter described, thesame cycles from its predetermined deactuated stroke position of FIG. 2to its predetermined actuated stroke position of FIG. whereby it can beseen that the actuator arms 49 and 49' are moved vertically upwardlyfrom the position illustrated in FIG. 2 to the position illustrated inFIG. 5 whereby such movement of the cam arm 60 rotates the cylindricalcam member 59 in the circular bore 48 so as to rock or pivot the arm 28toward the arm 29 to longitudinally compress the crystal stack 12therebetween.

Conversely, when the actuator 41 moves from its actuated stroke positionof FIG. 5 back to its deactuated stroke position of FIG. 2, the arms 28and 29 are pivoted away from each other by the cam member 59 rotating inthe bore 58 so that the previously described longitudinal compressiveforce on the crystal stack 12 is relieved whereby the crystal means 16can longitudinally expand.

Thus, as the actuator 41 is reciprocated between its predeterminedactuated stroke position and its deactuated stroke position in a mannerhereinafter described, the arms 28 and 29 are pivoted toward each otherand then away from each other to alternately apply a squeezing actionand a squeeze relieving action on the crystal means 16 to cause sparkingat the spark gap 15.

in particular. as the arms 28 and 29 are being pivoted toward each otherto longitudinally compress the crystal means 16 therebetween, apotential is being created at the electrode 13 and when the potentialdifferential between the electrode 13 and the grounded pilot burnermeans 14 reaches a predetermined magnitude, a discharge occurs acrossthe spark gap 15 in the form of sparks which will tend to ignite fuelissuing from the outlet end 17 of the burner means 14. Such sparking atthe spark gap 15 can take place one or more times during thelongitudinal compressing of the crystal means 16 depending upon theamount of pivoting movement of the arms 28 and 29 toward each other.Conversely, as the arms 28 and 29 begin to pivot away from each other soas to relieve the longitudinal compressive force previously imposed onthe crystal means 16, the expanding crystal means 16 is also having thestresses therein altered to cause sparking one or more times at thespark gap 15.

Therefore, it can be seen that a large compressive force can be imposedupon the crystal means 16 by the pivoting arm means 28 and 29 in muchthe same manner as provided by a nut cracker or the like.

The plate 45 of the actuator 41 has a passage means 66 formed centrallytherethrough so as to be adapted to be disposed in fluid communicationwith the chamber 48, the plate 45 having an annular valve seat 67surrounding the inner end of the passage means 66 and projecting intothe chamber 48. The passage means 66 passes through a tubular extension68 formed on the outside of the plate 45 between the arms 49 and 49'thereof so as to be telescoped within a flexible tubular conduit 69 thatleads from a pneumatic source 70.

For example, the pneumatic source 70 is a vacuum pump so as to provide avacuum source for operating the actuator 41. A selector valve 71 isdisposed in the conduit means 69 intermediate the vacuum source 70 andthe actuator 41 to selectively connect or disconnect the vacuum source70 therefrom for a purpose hereinafter described.

Another passage means 72 is provided for the actuator 41 and is formedin the housing means or frame means 11 so as to interconnect anatmosphere port 73 with an annular valve seat 74 surrounding the passagemeans 72 and projecting into the chamber 48 of the actuator 41, thepassage means 72 being stepped in the housing means 11 to define a pairof internal shoulder means 75 and 76.

A porous filtering material or member 77 is disposed in the passagemeans 72 intermediate the atmosphere port 73 and the valve seat 74 forfiltering air flow through the passage means 72.

A flexible valve member 78 is movably carried by the housing means 11and has a valve stem 79 projecting through the valve seat 74 into thepassage means 72 and terminating at a fixed disc member 80 at the upperend thereof as illustrated in FIG. 2. A compression spring 81 isdisposed in the passage means 72 and has one end 82 bearing against theshoulder 75 and the other end 83 thereof bearing against the disc member80 so as to normally tend to maintain the valve member 78 in sealingrelationship against the valve seat 74 so as to close the passage means72 from the chamber 48 of the actuator 41.

The operation of the actuator 41 for controlling the aforementionedsqueezing action and subsequent squeeze relieving action on the crystalstack 12 will now be described.

When the housewife or the like desires to turn on the main burner means18 of the cooking apparatus by operating the respective selector knobtherefor (not shown) and the burner means 18 does not ignite because ofthe pilot burner means 14 being unlit, or when she actually notices thatthe pilot burner means 14 has been extinguished for some reason, thehousewife or the like can effect the ignition of the pilot burner means14 by causing the actuator 41 to repetitively cycle between itspredetermined actuated stroke position of FIG. 2 by operating theselector means 71.

in particular, the selector valve 71 can be manually operated so thatthe housewife or the like must manually maintain the same in its on"position for a desired length of time or the selector means 71 can be atimer operated valve means which when initially actuated willinterconnect the vacuum source 70 to the actuator 41 for a predeterminedperiod of time after the lapse of which the timer means will turn thevalve means 71 to its off position to terminate the operation of theignition means 10.

in any event, when the vacuum source 70 is initially interconnected tothe actuator 41, it can be seen that since the valve member 78 isdisposed against the valve seat 74, the vacuum source 70 can begin toevacuate the chamber 48 whereby the resulting pressure differentialacross the diaphragm 43 causes the movable wall means 42 to moveupwardly from the position illustrated in FIG. 2 to the positionillustrated in FIG. 5 whereby the arms 28 and 29 are pivoted toward eachother to provide the aforementioned sparking at the spark gap 15. Whenthe movable wall 42 reaches the position illustrated in FIG. 5, it canbe seen that the valve seat 67 on the movable wall 42 now engages thevalve member 78 to seal closed the valve seat 67 from the chamber 48 sothat further evacuation thereof cannot take place as the vacuum source70 is effectively disconnected from the chamber 48. However, because thevalve seat 67 is relatively large in relation to the valve seat 74, theamount of vacuum increases under the valve member 78 so that theresulting pressure differential across the valve member 78 at the valveseats 67 and 74 causes the valve member 78 to be flexed downwardly intothe valve seat 67 as illustrated in FIG. 6 in opposition to the force ofthe compression spring 81 so as to open the valve seat 74.

With the valve seat 74 now opened and with the valve seat 67 now closedby the flexed valve member 78 as illustrated in FIG. 6, the atmosphereis adapted to pass from the atmosphere port 73, through the passagemeans 72 and open valve seat 74, into the chamber 48 so that thedecreasing pressure differential across the diaphragm 43 permits themovable wall 42 to move downwardly from the position illustrated in FIG.6 to the piston illustrated in FIG. 7 by the force of the legs 28 and 29being pivoted outwardly by the previously compressed piezoelectriccrystal means 12, the valve member 78 being carried therewith because ofthe aforementioned pressure differential across the valve member 78whereby the valve stem 79 moves therewith and compresses the compressionspring 81. However, when the movable wall 42 reaches the positionillustrated in FIG. 7, the valve disc 80 bottoms out against theshoulder 76 of the housing means 11 to prevent further downward movementof the valve member 78 so that further downward movement of the movablewall 42 from the position illustrated in FIG. 7 to the positionillustrated in FIG. 2 causes the valve seat 67 to move away from thevalve member 78 and thereby open the passage means 66 to the chamber 48.When the movable wall 42 moves away from the valve member 78, thepressure differential across the valve member 78 ceases to exist wherebythe compression spring 81 snaps the valve member 78 upwardly to theposition illustrated in FIG. 2 to again seal closed the valve seat 74.

With the valve seat 74 now closed, the vacuum source can now begin toevacuate the chamber 48 in the manner previously described to again movethe movable wall 42 from its predetermined deactuated stroke position ofFIG. 2 back to its predetermined actuated stroke position of FIG. 5.

Therefore, it can be seen that the actuator 41 will continue to cyclebetween its predetermined deactuated stroke position and itspredetermined actuated stroke position as long as the vacuum source 70is interconnected thereto by the selector valve means 71, such cyclingof the actuator 41 causing the aforementioned cycling of the pivot arms28 and 29 toward each other and away from each other to cause sparkingat the spark gap 15 in the manner previously described.

Therefore, it can be seen that this invention not only provides animproved ignition means for a cooking apparatus or the like, but alsothis invention provides an improved pneumatically operated actuator forsuch an ignition means or the like.

Further, it can be seen that the pneumatically operated actuator of thisinvention can be used for purposes other than just with the sparkigniting means of this invention.

What is claimed is:

1. A pneumatically operated actuator comprising a housing means carryinga movable wall that cooperates therewith to define a chambertherebetween, said actuator having a first passage means leading to saidchamber and being adapted to be interconnected to a pneumatic source,said actuator having a second passage means leading to said chamber andbeing adapted to be interconnected to the atmosphere, a single valvemember movably carried by said housing means for opening said firstpassage means and closing said second passage means when said movablewall is in a predetermined deactuated stroke position thereof and forclosing said first passage means and opening said second passage meanswhen said movable wall is in a predetermined actuated stroke positionthereof whereby said movable wall is cycled between said predeterminedpositions thereof as long as said source is interconnected to saidchamber, said first passage means passing through said movable wall andsaid second passage passing through said housing, and a spring meanscarried by said housing means and being operatively interconnected tosaid valve member to tend to move said valve member to close said secondpassage means and open said first passage means.

2. A pneumatically operated actuator comprising a housing means carryinga movable wall that cooperates therewith to define a chambertherebetween, said actuator having a first passage means leading to saidchamber and being adapted to be interconnected to a pneumatic source,said actuator having a second passage means leading to said chamber andbeing adapted to be interconnected to the atmosphere, and a single valvemember movably carried by said housing means for opening said firstpassage means and closing said second passage means when said movablewall is in a predetermined deactuated stroke position thereof and forclosing said first passage means and opening said second passage meanswhen said movable wall is in a predetermined actuated stroke positionthereof whereby said movable wall is cycled between said predeterminedpositions thereof as long as said source is interconnected to saidchamber, said first passage means passing through said movable wall andsaid second passage passing through said housing. said first passagemeans terminating at a first valve seat carried by said movable wall andprojecting into said chamber, said valve member being flexible, saidhousing means having a second valve seat at the terminal end of saidsecond passage means and projecting into said chamber so as to face saidfirst valve seat whereby said valve member is movable between saidseats, said first and second valve seats being annular and said firstvalve seat having a greater diameter than the diameter of said secondvalve seat whereby said valve member is adapted to be bowed away fromseating engagement with said second valve seat when said first valveseat also seats against said valve member.

t i I I.

1. A pneumatically operated actuator comprising a housing means carryinga movable wall that cooperates therewith to define a chambertherebetween, said actuator having a first passage means leading to saidchamber and being adapted to be interconnected to a pneumatic source,said actuator having a second passage means leading to said chamber andbeing adapted to be interconnected to the atmosphere, a single valvemember movably carried by said housing means for opening said firstpassage means and closing said second passage means when said movablewall is in a predetermined deactuated stroke position thereof and forclosing said first passage means and opening said second passage meanswhen said movable wall is in a predetermined actuated stroke positionthereof whereby said movable wall is cycled between said predeterminedpositions thereof as long as said source is interconnected to saidchamber, said first passage means passing through said movable wall andsaid second passage passing through said housing, and a spring meanscarried by said housing means and being operatively interconnected tosaid valve member to tend to move said valve member to close said secondpassage means and open said first passage means.
 2. A pneumaticallyoperated actuator comprising a housing means carrying a movable wallthat cooperates therewith to define a chamber therebetween, saidactuator having a first passage means leading to said chamber and beingadapted to be interconnected to a pneumatic source, said actuator havinga second passage means leading to said chamber and being adapted to beinterconnected to the atmosphere, and a single valve member movablycarried by said housing means for opening said first passage means andclosing said second passage means when said movable wall is in apredetermined deactuated stroke position thereof and for closing saidfirst passage means and opening said second passage means when saidmovable wall is in a predetermined actuated stroke position thereofwhereby said movable wall is cycled between said predetermined positionsthereof as long as said source is interconnected to said chamber, saidfirst passage means passing through said movable wall and said secondpassage passing through said housing, said first passage meansterminating at a first valve seat carried by said movable wall andprojecting into said chamber, said valve member being flexible, saidhousing means having a second valve seat at the terminal end of saidsecond passage means and projecting into said chamber so as to face saidfirst valve seat whereby said valve member is movable between saidseats, said first and second valve seats being annular and said firstvalve seat having a greater diameter than the diameter of said secondvalve seat whereby said valve member is adapted to be bowed away fromseating engagement with said second valve seat when said first valveseat also seats against said valve member.